Initial fork commit

scripts/geodata/distance/haversine.py

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+# -*- coding: utf-8 -*-
+import math
+
+EARTH_RADIUS_KM = 6373
+
+
+def haversine_distance(lat1, lon1, lat2, lon2, radius=EARTH_RADIUS_KM):
+    """Calculate the Haversine distance between two lat/lon pairs, given by:
+    a = sin²(Δφ/2) + cos φ1 ⋅ cos φ2 ⋅ sin²(Δλ/2)
+    c = 2 ⋅ atan2( √a, √(1−a) )
+    d = R ⋅ c
+
+    where R is the radius of the Earth (in kilometers). By default we use 6373 km,
+    a radius optimized for calculating distances at approximately 39 degrees from
+    the equator i.e. Washington, DC
+
+    :param lat1: first latitude
+    :param lon1: first longitude (use negative range for longitudes West of the Prime Meridian)
+    :param lat2: second latitude
+    :param lon2: second longitude (use negative range for longitudes West of the Prime Meridian)
+    :param radius: radius of the Earth in (miles|kilometers) depending on the desired units
+    """
+    lat1 = math.radians(lat1)
+    lat2 = math.radians(lat2)
+    lon1 = math.radians(lon1)
+    lon2 = math.radians(lon2)
+
+    dlon = lon2 - lon1
+    dlat = lat2 - lat1
+    a = (math.sin(dlat / 2.0)) ** 2 + math.cos(lat1) * math.cos(lat2) * (math.sin(dlon/2.0)) ** 2
+    c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a))
+    d = radius * c
+    return d